Bone morphogenetic protein-2 (BMP-2) is important in the control of both skeletal morphogenesis and postnatal bone formation. However, little is known of the factors that regulate BMP-2 expression. Therefore, there is a great need to identify molecular mechanisms that are involved in the regulation of BMP-2 gene expression in osteogenesis, which serves as the short term goal of the candidate. The immediate objective of this proposal is to test the hypothesis that the zinc finger protein Gli2 influences bone formation by its regulatory effects on BMP-2 expression. The candidate's long-term goal is to develop an independent research career and to establish a solid multi-funded program on the studies of molecular mechanisms underlying the activation of bone formation, specifically focusing on bone anabolic signaling and gene regulation. The candidate will use this K01 to acquire additional skills in bone molecular biology. The mentors, Dr. Mundy and Dr. Harris, renowned experts in the field of bone biology, will provide excellent training experience for the candidate in "state of the art" institutional facilities at UTHSC at San Antonio. During phase I of the award, the candidate will benefit from the scientific guidance of two mentors. By phase II, the candidate will become a fully independent investigator. Genetic studies have shown that disruption of transcription factor GN2 results in severe bone defects, and our preliminary data suggests that GH2 up-regulates BMP-2 gene transcription. The proposed studies seek to confirm these preliminary observations, and to elucidate the mechanisms mediating the effect of GH2 on BMP-2 expression as well as on subsequent osteoblast differentiation and bone formation. Four specific aims are proposed (1) to determine the effects of loss-of-function of GH2 on osteoblast differentiation and BMP-2 gene expression, (2) to determine the molecular mechanisms by which Gli2 transactivates BMP-2 gene, (3) to examine the effects of overexpression of GH2 on bone formation in vivo in Gli2 transgenic mice and (4) to investigate the effects of the E3 ubiquitin ligase beta-TrCP on GH2 processing in osteoblasts. Full characterization of the roles of Gli2 protein in the regulation of BMP-2 gene expression and skeletogenesis should lead to insights into the molecular mechanisms of bone anabolic regulation. [unreadable] [unreadable]